Nigel Calder in the Times

As a prelude to a new book, Nigel Calder (who was the editor of New Scientist for four years in the 1960s) has written an op-ed for the Times (UK) basically recapitulating the hype over the Svensmark cosmic ray/climate experiments we reported on a couple of month ago (see Taking Cosmic Rays for a spin). At the time we pointed out that while the experiments were potentially of interest, they are a long way from actually demonstrating an influence of cosmic rays on the real world climate, and in no way justify the hyperbole that Svensmark and colleagues put into their press releases and more ‘popular’ pieces. Even if the evidence for solar forcing were legitimate, any bizarre calculus that takes evidence for solar forcing of climate as evidence against greenhouse gases for current climate change is simply wrong. Whether cosmic rays are correlated with climate or not, they have been regularly measured by the neutron monitor at Climax Station (Colorado) since 1953 and show no long term trend. No trend = no explanation for current changes.

213 Responses to “Nigel Calder in the Times”

“(Missing step #4). Finally, to show that cosmic rays were actually responsible for some part of the recent warming you would need to show that there was actually a decreasing trend in cosmic rays over recent decades – which is tricky, because there hasn’t been (see the figure)”

The figure comparing CR flux vs. temperature cuts a fine figure, but the CR measurement displayed is for neutrons. Muons are the relevant form of CR, since they’re implicated in cloud formation. In Svensmark’s 1999 article, it would be possible to draw a statistically justifiable slightly downward sloping line through his muon data, as detected by ionization chambers, 1937-1994 & shown in his Figure 3. I don’t know if it could be extended to 2006 at the same inclination.

Suffice it to say that neutron detectors & muon measuring ionization chambers or telescopes show slightly different GCR fluxes. The muons are relevant, as per my prior probably overly cryptic comment & link to discussion of muons at the SLAC site.

However, it seems to me that Svensmark concentrates more on apparent correlation or coincidence of GCR & solar cycles than on trendlines over shorter time frames, such as 22 year cycle for the reversal of the Sun’s magnetic field, the ~11 year sunspot cycle & peak years within each cycle.

Little Ice Age — probably real. Paleoclimate reconstructions (hockey sticks) show a cooler period from about 1450 to 1800, but the total cooling, even in the most highly-varying reconstructions (Moberg et al.), amounts to only about 0.5 deg.C, and in other reconstructions is much less. We’ve already seen more warming than that in just the last century.

Lack of sunspots at the same time — not so. Sunspot counts only begin in earnest in the mid-1600s; there have been a number of minima in sunspots counts (most notably the “Maunder minimu”) but the record shows large variations, not only during the “little ice age” but after that as well.

Coincidence — probably not. Solar forcing is known to be an important factor in climate change (contrary to contrarians, it is not ignored or underestimated by climate scientists), and may have been an important player in climate changes over the last few thousand years. But there are other players as well, most notably volcanic eruptions. Also, the changes in temperature in the last few thousand years are considerably smaller than what we’ve seen in the last century, and are vastly smaller than what we expect to see in the next century.

Real. Period before & after a low in the 1690s was remarkably cold, certainly in a good chunk of the “temperate”, subarctic & arctic NH at the very least, as you must know. Googling produces copious excellent, coherent studies from disparate proxies & actual thermometer readings of various qualities. The early 19th century dip has been associated with Tambora blowing in 1815, of course but the secular trend was in any case cool until ~1850.

The lack of sunspots at the same time – real or not?

Maunder Minimum is well documented, despite imperfection of sunspot record in that period, generally assessed as 1645 to 1715, confirmed by C14 & Be10 data.

Is it a coincidence – yes or no?

It’s definitely a coincidence, but possibly not merely so. It could be a meaningful correlation. How significant, lots of work may soon be funded to determine. Are we at the beginning of a new paradigm shift, replacing 20 years of greenhouse gas AGW consensus building? Possibly. The climate itself in coming decades will help answer that & your questions, along with experimentation & rejiggered computer simulations.

Sunspots aren’t as scary as runaway CO2 feedback scenarios, but there should still be plenty of funding to keep paleoclimatologists, geophysicists & other climate & atmospheric scientists busy, maybe bringing more astrophysicists, statisticians & mathematicians into the fold well into the next 22 year solar magnetic cycle. Maybe by then we’ll be worrying about global cooling again, as in the 1970s, scanning the northern horizon for the advancing ice sheets.

Whose fault ? :D It appears there’s nothing new in Nigel Calder op-ed. So, does it deserve a discussion? And how could we expect new insights on these over-debated topics?

Before adressing GCR-nebulosity question, I suggest it would be more useful to get correct nebulosity climatologies. An article on what we know and don’t know from current measures (e.g. ISCCP, BSRN, ERBS, HIRS, AVHRR, etc.) would be interesting. IPCC AR4 mentions it as an “important develoment since the TAR”.

All the contrarian theorists seem to have missed an important point, which is that while climate certainly is affected by solar variations, volcanic activity, and so on (maybe even cosmic rays, though as mentioned it’s hard to see how a lack of variation could produce climate changes), if you want to use any of these as a complete alternative model of current climate trends, you have a twofold problem. First, you have to incorporate your theory and data into some sort of model that gives results that match actual observations. Second, you have to find a way to explain why the measured increase in CO2 is _not_ producing the effects that theory and experiment predict it should.

As far as I can tell, very few have even tried to do the first, and almost nobody the second. Which to my way of thinking puts these theories into the same class as science-fictional “warp drives”: something thought up to get the result the author wants :-)

“Why no, the people doing this work are totally unaware of such things!

That scientists trying to understand AGW are librel, perhaps even commie, conspiracy people who don’t actually pay attention to stuff that appears in undergrad science textbooks.”

Actually, I’m generally interested in the concept of warming/cooling cycles and the variables which may drive them, as is Nigel Calder. But I’m also interested in whether of not Cognitive Dissonance is having a greater impact on bias in AGW science than hard evidence. It is my firm belief that c.d. is the greatest single psychological factor responsible for unintended bias in scientific experimentation – partially because it is as prevalent in highly educated people as it is in the common man.

I thought that the term was GLOBAL WARMING and not LOCAL WARMING as was the MWP or LOCAL COOLING was LIA. Anyway the article is publiched in the daily telegraph (DT) here under one of the most viewed items.

The DT is a well known right wing newspaper that seems to print all things climate skeptical, we remember Mr Monkston and Bob Carter don’t we. However they did print a rebuttal from Al Gore to Mr Monkston so fairs fair I suppose.

One thing that this article does suggest however is the notion of the little knowns in climate science, ice dynamics is one area I believe especially in the area of how fast ice sheets will move but I guess that real data can help here refine the mathematics. Cloud formation is another area as well as others. I mean is the uncertainty in the projected climate temperatures from slightly differing models due to little knowns in current climate science or by chaos theory (sensitivity to initial conditions that project out after a long period of time) perhaps. 1.5 to 4.5 Deg C even after a lot more spending is not that much more accurate than climate models run 20 years ago is it ?

Can we get more accurate climate models and if not then why not ?

I would also like to be told why CO2 levels of 700 or 900 ppm means no greater temperatures than 550 ppm which is what we are currently heading for by around 2090.

Before creating new models, we may simply hope that present GCMs better cope with all climate forcings and parameters. Model intercomparisons is a good way for that. Is solar correctly implemented (even without the so hyped GCR effect, masked TSI trends, etc.)? A recent contribution of Raschke and al. (link thereafter) suggest a negative answer. I quote them :

“A careful intercomparison of recently released data sets on the radiation climatologies as computed in the projects ISCCP-FD and GEWEX-SRB showed considerable differences of more than 20 to 50 Wm-2 in monthly averages of radiation flux products at the top of the atmosphere (TOA) and at ground for large latitudinal zones covering up to 25% of the Earth’s surface.”
Raschke, E.; Kinne, S.; Gorgietta, M.; Uphoff, M.; Bakan, S.; Okamoto, H.
Inconsistencies of the incoming solar radiation boundary condition in global modeling

Re 5 and 6
Interesting question. I couldn’t find the link but I think I read that this particular die off is disease related.
However it does beg the question if AGW is a stressor that makes individual species such as bees or corals more susceptible to disease in general.

However if you think modeling the complexities of climate is difficult you should talk to some biologists studying interconnected ecosystems, I think they’d tell you that modeling those systems is a couple of orders of magnitude more difficult.

Based on some of the opinions I have read here and elsewhere it seems that gleaning information from such models is probably a useless excersise since the current models are probably not sophisticated enough and there is just too much we don’t know. So let’s roll up our sleeves and get back to chopping and burning down the forests shall we.

It’s hard to see how to reconcile the sine/cosine style pulse of the cosmic ray record with the steady increase in temps. If there’s any effect at all, it has to be real tiny because it’s getting swamped by the effect of greenhouse gases.

James (55). A response to your challenges is quite easy. As an experienced computer modeller (albeit not of climate), I know it is easy to produce “some sort of model” to show pretty well anything you want. The climate models (as with most computer models) are highly sensitive to the assumptions made by those who develop them. Models are not proof, although a very useful tool for those who can use them with honesty and integrity. With regard to AGW theory, this predicts an accelerating rise in temperatures. In contrast, the trend has not increased since at least 2002 (some would say 1998). While AGW advocates can come up with explanations why there is currently no rising trend (despite having the highest CO2 emission rates ever), you cannot deny that this is a mismatch to the theory.

[Response: Maybe you’d care to point us to the publication that predicts that temperatures must increase year on year in AGW simulations? Or the model run that says that interannual variability vanishes once CO2 reaches 380ppm? The first step in testing a theory is being clear about what is predicted. -gavin]

I’ve been arguing this very story on slashdot for a day or so, thanks for tackling it head on.

One minor but I think important point: After posting the “Taking cosmic rays for a spin” story as comment on slashdot several replies said it does not adequately state what is wrong with the CR – climate change link, and I think they have a fair point.

A much stronger (and more civil) argument is made by this RC story. Only a suggestion but you might want to add the link to this article while it’s still fresh.

The nice thing about science is that it provides a way around cognitive dissonance (the experiment). Dream up any theory you like, if it doesn’t fit the experimental data, CD won’t save you.

If anybody has a CD problem, clearly it’s the contrarians, as they are ignoring tons of evidence. On top of that, they are (in effect) denying the basic mechanism:
1- CO2 traps heat (known since more than a century)
2- We are putting lots of CO2 into the atmosphere (undisputed)
3- The temperature goes up (and lo and behold, that what we see)
That is, warming is to be expected: we should be very surprised if there were NO warming.

then I don’t see any reason why different energy bands will be trending differently than the ones monitored at CLIMAX.

Well, the lower energy GCRs should be more strongly modulated than the more energetic GCRs (since interplanetary magnetic fields in the solar wind and at the heliopause affect the former more strongly than the latter), but I agree I don’t see why the trends should be qualitatively different. If anything, the signal should be stronger in the lower energy GCRs than in the higher.

Isotope evidence (10Be, 14C) is, I imagine, more of a proxy for the lower energy GCRs than the energetic ones that make muons that can reach low alitudes, since the flux of the former is much greater. I hope none of the contrarians are touting this evidence to support a theory that involves higher energy GCRs while dismissing the recent neutron data.

If there really is a connection between GCRs and cloudiness, it offers the possibility of new geoengineering approaches to mitigating global warming. The total energy in cosmic rays hitting the Earth isn’t all that large (and even less in the more energetic ones), so it’s conceivable it could be artificially enhanced with accelerators in space. A whacky idea, but amusing to consider.

This is great! If true, it would mean we can expect some cooling when the rays decrease. Of course, until it’s proven to be the only cause of GW (and GHGs have no noticible impact), then we do still have to keep reducing our GHGs….in fact, it just makes economic & (other) environmental sense to reduce our GHGs whatever the situation re GW.

As for funds to conduct research, have they tried Exxon? Or is it that even Exxon has serious doubts about their research.

Re: Dick V (62)
I trust most readers can see the irony in the following statement by DV:

“If anybody has a CD problem, clearly it’s the contrarians, as they are ignoring tons of evidence. On top of that, they are (in effect) denying the basic mechanism:”

While I respect the right of AGW advocates to have their views (hopefully derived from an assessment of the arguments rather than blind faith, or the naive emotion of seeing photos of polar bears standing on melting ice), there are too many AGW zealots who happen to ignore “tons” of uncertainty, arriving at the nonsensical view that ‘the argument is settled’.
As for ‘denying the mechanism’, I think there are very few who would deny the theory. The issue is whether the mechanism is significant. We emit many pollutants and do many things that impact on our environment, but this does not automatically mean they have a significant or devastating impact. It is my view, having followed and assesed the arguments closely for years, that the case for AGW is far from made – and I am far from alone (even if I may feel in a minority). The debate lives on!

Simple question from the back row. If the sun and cosmic radiation have nothing to do with global warming then what exactly caused global warming in prehistory? Please email me with the answer so I can understand why climate change now has to be caused by man and cannot be caused by factors beyond our control. Does this mean that once man controls his excesses there will be no more climate change?

[there are too many AGW zealots who happen to ignore “tons” of uncertainty, arriving at the nonsensical view that ‘the argument is settled’.]

That raises several questions and begs clarification.

Do YOU really measure scientific reports and analyses “of uncertainty” in “tons”? How about a pound or two of actual peer-reviewed, published reports on uncertainty so that we can all digest their content and come to the same or similar conclusions as you? Give us links and titles so we can read what you are reading.

As regards zealots, I hope you can differentiate zealots from scientists and well read lay persons who contribute to RealClimate. I agree that photos of stranded polar bears will not cause Texas Utilities to reassess plans to construct 11 coal-burning power plants. But Australian drought is being measured in lost economic growth for 2006 and honest scientists there are projection more of the same and worse.

If you are a parent, you might reconsider your watch and wait attitude. Might be there are more things to take into consideration than your uneasy feeling about the preponderance of evidence that your approach spells hurt for future generations.

Maybe the reason you feel in a minority is you lack the ability to process and act upon information that challenges your comfort level.

Lets look at it this way……If the earth was the size of a roughly a large house, a supertanker is visible as a miilimeter sized sliver moving along the ocean. Taking into effect all the stored carbon released the past 200 or so years from all the industrial revolution factories, would it impact this large ball? Decidedly, yes. If I smoke a cigar in a large room, will the people coming in an hour later detect this stench? Again, the answer is yes. The anomoly here is not this sphere with all inside it, it is the impact the human inhabitants are making on it.

Any veteran inquisitive scientist trying out a new Chinese restaurant can try out the hot and sour soup, and depending on it being to his or her liking or not, can make certain inferences about the rest of the meal. And so it is with the carbon spike in the earth’s atmosphere and what future implications one can infer from this spike. I for one am guilty of being innocent of going with my intuition, but am learning to go with the facts presented before me, and sanely and intelligently putting aside my emotions and innocent intuition and embracing the facts. Two things I know……There is no Santa Claus, and the earth is heating up due to man’s poor stewardship.

To reply to gavin’s challenge in no. 61:
I don’t suggest that temperatures must increase year-on-year, or that there should be no interannual variability. The theory predicts that temperature will rise as CO2 rises. We know that the rates of CO2 emissions are increasing year-on-year and that atmospheric CO2 concentrations are rising steeply now compared to the first half of 20th century (AR4 Fig SPM-1). It is difficult to reconcile this evidence with (i) the much greater IPCC certainty that AGW is significant and (ii) that the rate of temperature rise has reduced in the last 5 to 10 years (AR4 fig SPM-3) rather than giving any sense of an increasing rate to match the CO2 trend.

On the doubling (or not) of the Sun’s coronal magnetic field in the past 100 years (Lockwood, et al, 1999, from Nature, cited below), there is now a decent body of research from around the world, both confirming & denying this finding in all or part.

Should a secular increase in IMF be shown, it would of course remain to be demonstrated what observable or plausibly reconstructible effect this had on some parts or all of our planet.

While muon flux as measured far above, just above, at or below the earth’s surface may or may not show a downtrend globally, this could be an experimental artifact, as the record isn’t geographically complete or temporally long enough. There could be regional effects, perhaps related to the solar & terrestrial magnetic fields, like the auroras.

As is usually the case, we need to know more. Or at least I do. Maybe someone else doesn’t.

[Response: So what is the positive evidence that muon flux has changed in recent decades? It’s not sufficient to assert that it might have done and so there might be an unquantified effect on climate. Occam’s razor starts to come into play here…. – gavin]

RE: #73 – As with all systems, the bugaboo in the stability analysis is the parasitics. Do they result in an asymptotic situation, where, when you approach the “safe operating envelope,” the parasitics result in a “fold back” innately due to their increasing contribution to energy dissipation? Or are they more in the realm of something that adds to the main “control loop” and results in a “runaway” situation? The prevailing theory of the orthodoxy appears to be something like the latter, albeit on a limited scale (for example, the “runaway” in this case would not be at the total system level but only within the behavior of the parasitic terms, resulting in a new “higher equilibrium”). My own experiences with complex systems suggest that as you scale, the sorts of mechanisms that might result in a complete system runaway or even a runaway of some parasitic term across the system, become more and more implausible. That’s because with increasing scale and complexity, the opportunities for loss of efficiency and internally dissipative mechanisms increase. Consider grid lock.

What you are saying seems to me to be a big part one of two of why there is a debate:

Part one:

1- CO2 traps heat (known since more than a century)
2- We are putting lots of CO2 into the atmosphere (undisputed)
3- The temperature goes up (and lo and behold, that what we see)
That is, warming is to be expected: we should be very surprised if there were NO warming.

This makes sense, but raises the question – is the AGW consensus based on assigning the observed warming to GHG’s primarily? Do I have this right?

And, if other forcing factors are discovered, wouldn’t we have to remove some of the correlated value assigned to GHG’s? And, if the other forcing factors are cyclical and likely to turn down eventually, doesn’t this mean that some long term projections for AGW effects have to be revised?

As to part two:

I ask these questions because, I’m not a scientist, but I believe the recommendation is to reduce GHG emission by 50% over some period (soon). Given that fossil fuel energy is a huge driver of the global economy, I think it behooves all of us to examine the projections carefully.

From what I can interpret in the SPM Radiative Forcing Chart, there is what looks to me to be a lot of uncertainty regarding cloud cooling and its interaction with aerosols. Does this relate to the debate over GCR or is it a separate issue? Or to rephrase that, can aerosols and GCR both be factors that when better understood will remove the uncertainty depicted in the SPM?

Am I missing something obvious here? How can total cosmic rays be inferred from neutron monitors? A neutron is uncharged so you wouldn’t expect any variation corresponding to changes in the solar magnetic field. The charged particles obviously would be affected.

A reply to PHE (#73): First, the graph you actually want to compare the temperature trend to is the calculated total forcing (made up of GHG concentrations – CO2, CH4, N2O, etc. – and aerosol forcing). CO2 may be the largest contributor to forcing, but it is not the only one. Methane at least has hit a plateau for the last decade, though it is not obvious if this is a temporary pause or a long term one. But my guess is that the total forcing will follow a roughly linear trend for the past couple decades. (And in fact, even for just CO2, because of the logarithmic relationship of concentration to forcing, you expect a linear forcing trend from an accelerating emission trend)

Second: You are microanalyzing short term trends in what is a long term phenomena. It might be interesting for you to take said forcing graph, assume that temperature scales exactly proportionally, but then add “noise” to the temperature plot. Run this 100 times. For a decent number of cases even if the underlying equation is accelerating you’ll still get a temporary reduced rate of rise in the last few years. One outlier (like 1998) can make a large difference in any short term analysis.

I presume you’re asking about what caused global warming during the ice ages.

Small changes in the orbit of the earth, and in the tilt of earth’s axis, can cause sizeable changes in the distribution of incoming sunlight. Greater axial tilt, for example, causes more solar energy to reach the polar regions while less reaches the tropics, and this can lead directly to the decay of ice sheets near the poles.

When the ice sheets shrink, this reduces the earth’s overall reflectivity (ice is highly reflective but land and sea are not). This causes more incoming solar energy to be absorbed into the climate system rather than reflected back to space, and this warms the planet as a whole.

When the planet warms, so do the oceans. Warmer oceans will hold less CO2, so that CO2 leaves the oceans and enters the atmosphere. Since CO2 is a greenhouse gas, this warms the planet even more. This causes more reduction in ice sheets, more CO2 released from ocean to atmosphere, which in turn causes more warming, etc… a classic “feedback mechanism.”

For a few more details and some graphs, see the links in my previous post #47.

These astronomically-related factors are very slow; the fastest cycle is precession, changes in the orientation of earth’s axis relative to perihelion (the point of closest approach to the sun), and this cycle is never less than about 19,000 years. So, they’re much to slow to explain modern global warming, which is very rapid — about twenty times faster than the warming rate during a reasonably rapid deglaciation.

If we reverse our climate-changing activities, there will still be natural climate change. But if the past is any indication, it will be slow enough that we’ll have plenty of time to adapt.

I just read Wong et al. 2006 (thereafter). Between 1980s and 1990s, their best estimate for TOA radiative flux over Tropics (20°N-20°S) is +0,7 W/m2 for LW and -2,1 W/m2 for SW. The later number implies a significant downward trend of albedo (probably nebulosity). More insolation leads to more ocean heat content, I suppose, and more energy to be redistributed from tropics to pole. Could we expect this decadal radiative trend is involved in the 90’s warming?

PS : if the ERBS measure is correct, it doesn’t plead in favour of Lindzen Iris effect, as Wong et al. conclude.

[[It is my view, having followed and assesed the arguments closely for years, that the case for AGW is far from made – and I am far from alone (even if I may feel in a minority). ]]

A distinct minority, especially among climatologists. Rather like those who still hold out hope for Einstein to be wrong about relativity. There are some of them, too, and they’d be quick to tell you the case for AGW is far from made.

[[Simple question from the back row. If the sun and cosmic radiation have nothing to do with global warming then what exactly caused global warming in prehistory? Please email me with the answer so I can understand why climate change now has to be caused by man and cannot be caused by factors beyond our control. Does this mean that once man controls his excesses there will be no more climate change? ]]

Nobody ever said manmade CO2 was the one and only possible cause of climate change. There are many things that have changed the climate in the past, and there are many things affecting it now. But the main item driving the present warming is manmade CO2. In short, your argument is a straw man.

As has been discussed here previously, neutrons are not the best indicator of total GCR, but more importantly are inappropriate for climatic studies. Muons are implicated in cloud formation, as shown in my SLAC link in comment #43.

The solar coronary magnetic field (IMF) does seem to have increased in the past hundred years. I posted objections to Lockwood’s assessment of doubling, but these researchers present a graph which appears to confirm it:

It might not be possible to download the IAU article from this link. If not, please if interested Google “reconstruction open solar magnetic field 19th 20th centuries ivanov miletsky” or some portion of these keywords. The authors reconstruct the IMF since 1844 & 1915.

[[I don’t suggest that temperatures must increase year-on-year, or that there should be no interannual variability. The theory predicts that temperature will rise as CO2 rises. We know that the rates of CO2 emissions are increasing year-on-year and that atmospheric CO2 concentrations are rising steeply now compared to the first half of 20th century (AR4 Fig SPM-1). It is difficult to reconcile this evidence with (i) the much greater IPCC certainty that AGW is significant and (ii) that the rate of temperature rise has reduced in the last 5 to 10 years (AR4 fig SPM-3) rather than giving any sense of an increasing rate to match the CO2 trend. ]]

I’d recommend a good course in statistics. You are trying to generalize from a sample of 5-10 years. The warming has been going on for over 100 years, though the most recent phase of it has lasted about 30. Mean global annual surface temperatures are a random walk around a steadily increasing mean.

#89 Tamino, I agree with your description with just some questions about ocean cooling / warming link to CO2 atmospheric rise during glacial/interglacial transition. As there is no change in total solar forcing (just an orbital/regional one centered on Northern Hemisphere, not on Southern oceans) and as there’s a great thermal inertia for oceans, how do we explain the relatively high and fast increase of CO2? Shouldn’t we expect a millienium rather than secular lag between Milankovitch forcing and CO2 response?

These are both pattern-matching arguments: that the temperature curve should mimic the shape of CO2 emissions or concentrations. Even if you neglect noise, which exists on many time scales, such expectations are incorrect. They ignore both the nonlinearities (e.g. forcing is proportional to log(concentration)) and the dynamics of the system (temperature is two integrations removed from emissions: CO2 must accumulate in the atmosphere, and the heat from the resulting forcing must accumulate in the atmosphere and ocean). To make a serious claim that reality and models are diverging, one must at least account for the basic physics and forcings of the system. A suitable model could fit on a napkin – the ball is in your court.

Concerning New Scientist 10th Feb 2007 edition (Vol 193, No. 2590) and its alarmist out of breath “This Week: Climate Change” article by (probably) Fred Pearce : a figure on page 9 is really the culmination of “immoral” alarmism: a graphical illustration tells about “the sun versus humans” and wants to depict the difference between the “natural solar radiation” (they forget to say: the increase of …) and human caused radiative forcing. According to the SPM this is about 1.6 W/m2 to 0.12 W/m2 (lets not discuss this here), so the relationship is about 13 to 1; the illustration draws a very tiny solar disk and a huge man-made-effects disk suggesting a 269 to 1 relationship (when you draw disks, please do not expect that the visual clue is to compare the diameters! it’s the surface, stupid!). [edit]

Apparently I was not clear enough in my post (apologies). What I meant was the following: suppose somebody has a theory in which phenomenon X is the cause of (most of) global warming – then clearly the burden is on him to provide an argument why the expected warming due to GHGs is NOT there, or is far less than we think it is (see post #55). If he doesn’t do that, he is in fact denying the basic greenhouse gas warming mechanism (of which we know it’s there).

As regards to how much different things contribute: personally I am impressed by how well current theory (embodied in models) reproduces measurements quantatively. It seems to me that GHGs (+ aerosols and a few other things) pretty much explain all observed warming.

Does that end all debate? Of course not, I just think that more than enough evidence is in to make an informed decision on mitigating policies now.

The Svensmark paper was interesting and innovative. However, it ignores the fact that there seems to be no measurable decrease in GCR flux in the 30 years we’ve had measures of it by satellites. I’ve looked at the GOES data myself, and the modulation over solar cycle stands out clearly, but there is no lont-term trend. Conversely, the solar-cycle modulation, which is a factor of 3-5 in GCR flux over 11 years does not seem to influence weather that much.
Look, if someone could come up with a forcing mechanism that could explain the trends other than anthropogenic CO2, nobody would be happier than me. However, no one has proposed a mechanism that is even plausible.
So, on the one hand, we have a mechanism that explains the trends pretty nicely and that we know is present and we have no competing hypothesis that approaches credibility. To reject a perfectly good model simply because you don’t like the implications is simply anti-scientific. If your opposition is to the policies that you think may be implemented, the place to get involved is at the policy level.

[This makes sense, but raises the question – is the AGW consensus based on assigning the observed warming to GHG’s primarily? Do I have this right?] I agree with Barton in #87: my understanding is that scientists don’t “assign” warming to GHGs to make predictions fit observed temperature rise: how much warming some GHG causes is determined in independent experiments.

[Cloud cooling and aerosols] I am really not qualified to answer this one. We’ll have to ask the good folks at RC.

This is the wrong topic I know, but was curious about this article: http://www.sciencemag.org/cgi/content/abstract/1138478v1
Since I can’t read Science I’m a bit curious to know what impact this have on the dynamic part of the modelling on glaciers. A step back to around 2001 or is there still evidence that the melting goes faster?

Calder is also making the argument that there are warming/cooling cycles in increments much smaller than 19,000 years – based on extensive historical evidence he claims is largely ignored by the AGW community. I don’t know that the book will cover such evidence, but want to read it before jumping to conclusions.

Interesting in the article about the California frost. I remember that thread about the January heatwave.In the NCDC website it said that while last month the eastern USA was a lot warmer than average the West was a lost colder. An average month?

#90
“I just think that more than enough evidence is in to make an informed decision on mitigating policies now”

Do we know if GHGs count for 50, 70, 90% of the last decades warming? No. Do we know if climate sensitivity is definitely constrained to 2-4,5 K and which value is really the most convincing? No.

Precaution principle probably commits us to take policy decisions, but I don’t think policymakers are better informed in 2007 than in 2001. Just look at low and high extremes of range for 2100 projections : 1,1-2,4 K versus 2,9-6,4 K. In the first case, a not so damaging warming for which adaptation would probably be a better option. In the second case, catastrophic warming against which a drastic and urgent reduction of GHGs emissions is needed.

Ray comments that Svensmark “ignores the fact that there seems to be no measurable decrease in GCR flux in the 30 years we’ve had measures of it by satellites. I’ve looked at the GOES data myself, and the modulation over solar cycle stands out clearly, but there is no long-term trend. Conversely, the solar-cycle modulation, which is a factor of 3-5 in GCR flux over 11 years does not seem to influence weather that much.”

What matters is muon flux in the lower atmosphere, more than overall flux in space. We don’t have a good record of that, but what we do showed an anomalous low in the ’90s followed by a lower than average high, but as Ray points out, in the regular pattern. A downtrend could be drawn through the data points. The muon series probably isn’t long enough, with adequate geographic coverage or even reliable enough upon which to base a firm conclusion.

There does seem to be or at least arguably is a detectable or reconstructible increase in solar IMF since the mid-19th century, so it’s not unreasonable to assume some effect from this on GCR in general & muon flux in particular. We may not have the capability now & surely not in the past to measure whether such modulation actually occurred or is occurring. We may however be able to infer it from future climatic observations, in lieu of other persuasive explanations, should earth not experience the changes forecast in AGW scenarios.

“Look, if someone could come up with a forcing mechanism that could explain the trends other than anthropogenic CO2, nobody would be happier than me. However, no one has proposed a mechanism that is even plausible.”

I feel that GCR forcing via nebulosity is at least a plausible mechanism, more readily subject to testing than AGW.

“So, on the one hand, we have a mechanism that explains the trends pretty nicely and that we know is present and we have no competing hypothesis that approaches credibility. To reject a perfectly good model simply because you don’t like the implications is simply anti-scientific. If your opposition is to the policies that you think may be implemented, the place to get involved is at the policy level.”

You probably know reputable atmospheric scientists who would not agree that AGW is a perfectly good model & that there are credible competing hypotheses, if not personally, then through their work. I do.

Few would doubt that human activity has had no effect on climate change. Ruddiman thinks it has for thousands of years. Life has had profound effect on climate, the land, sea & atmosphere for billions of years. The moot question to me is what part of observed climate change (setting aside the issue of how valid the observations, reconstructions & modeling may be) is anthropogenic & how much attributable to natural causes, which may be unknowable. Someone may be smart enough to know all of them, but I’m not.

I’d feel more comfortable with AGW if the atmosphere had detectably warmed up before & more than the land & sea, & if other causes could not produce the same responses generally cited as proof of AGW via the greenhouse effect. Even with the most extreme adjustments to satellite & balloon data, it appears last I checked that the areas that should have warmed first & most haven’t. Please correct me if wrong.

I am already involved on the policy level. There are good reasons to be concerned about burning fossil fuels, regardless of how much weight you give to AGW computer simulations.

Re JLMcC (69) ‘Tons’ was taken ironically from the words of Dick Veldkamp. A good reference on AGW uncertainties is IPCC TAR. Look at the sicence rather than the Summary [by] policymakers. As many here will tell you, one year/drought doesn’t make a rule (see gavin’s response to my comments). I have two young children, and what I recognise is that they now have the best prospects in the history of mankind – in life expectancy, healthcare, world peace, prosperity, etc. And we (in the developed world) are doing a pretty good of balancing our prosperity with environmental protection. I am what many Americans would derogatarily call a ‘liberal’. I am an environmentalist, but also a rational scientist who despairs at the distortion and misuse of science as I see in the ‘case’ for AGW.

Re Steve Sadlov (75). I like your satire.

Re Marcus (79) The graph I had in mind on Fig SPM-1 was the inset in the top graph which shows the rise in CO2 since about 1750. Nothing more complicated than that.

Re BPL (82). I suppose if scientific truth was based on a vote, you’d win. [edit – no politics]. The ridiculed minority are not necessarily wrong. That’s why its important to carefully assess the facts and feel the need to be convinced ‘yourself’ rather than to go with your heart, the flow, the popular view, etc.

Re BPL (85) You don’t need to convince me to be wary of short term data. First, direct it at all those who argue the current drought in Australia, Hurricane Katrina, the current mild winter in Europe, etc, are due to AGW. Second, try the AR4 Summary [by] Policymakers which argues the rate of sea level rise is increasing (1993-2003 compared to 1961-2003)when a look at their own Fig SPM-3 shows this is nothing more than selective statisitcs.

Re T. Fiddaman (88) I do not expect the absence of noise. My comments were intended to be ironic. Its the AGW advocates who seem to argue that a simple correlation between CO2 rise and temperature between (just) 1976 and 1998 (just 22 years!) is sufficient to claim impending doom. The only other period of 20th century temperature rise (1910 to 45) was at a time when CO2 emissions and levels were much lower and which IPCC TAR (amongst others) claims was due to natural effects. Individual droughts, hurricanes, mild winters are the natural noise that don’t make the rule. AGW advocates have not convincingly demonstrated that the current global temperature or rising trend is anything more than long period ‘noise’.

Re. D. Veldkamp (90) With regard to who has the burden of proof: whatever the theories, there is no convincing evidence that (i) current temperatures are exceptional in human history (ii) that the rate of rise is exceptional (almost identical to 1st half of 20th Century (iii) that the climate is currently undergoing exceptional change (though it is currently warming) (iv) that predictions of rising trends are anything more than an extrapolation of the present trend combined with the ASSUMPTION that CO2 is the cause, or (v) that rising temperatures will cause the postulated disasters. You will no doubt be convinced that all this is ‘obvious’ and proven. I recommend, however that you rely more on the science of AR4 (when it is published) and of others, than on the ‘medievel-style’ headlines of ‘the end of the world is nigh’ (Nothing new there then. While the climate continually changes, human nature changes little)